Use has already been made of such a type of inspection machine, wherein the rotary conveyor which operates with a driven endless conveying means and an opposite stationary friction surface is arranged at the feed conveyor at a distance in front of the intermediate conveyor, namely in the operative area of the single side-inspection device. Being of a compact construction, this prior-art inspection machine makes it possible to check containers for impurities, faults, etc., in both the bottom area and the wall area. The containers are handed over in a safe upright position to the discharge conveyor by the conveying means of the intermediate conveyor which are driven at the same speed. A disadvantage is, however, that the rotary conveyor can only engage the lowermost wall portion of the containers in order to avoid an excessively restricted field of vision of the side inspection device. Moreover, since a great rotary angle is required over a relatively short transportation path, the container transport in the area of the rotary conveyor is extremely unstable and the inspection result does not meet the requirements. Moreover, the containers might very easily tip over before being gripped by the intermediate conveyor after their passage through the rotary conveyor. The prior-art inspection machine is therefore not suited for high capacities.
Furthermore, use is made of an inspection machine comprising a feed conveyor, a discharge conveyor spaced apart from the feed conveyor, and an intermediate conveyor transferring the containers between feed conveyor and discharge conveyor, wherein a first side inspection device is arranged at the feed conveyor, a second side inspection device at the discharge conveyor and a bottom inspection device in the area of the gap existing between the feed conveyor and the discharge conveyor. The intermediate conveyor comprises two endless conveying means which engage opposite sides of the containers and are driven at different speeds and which rotate the containers traveling from the feed conveyor to the discharge conveyor by a specific angle. Hence, the containers are rotatingly fed from the intermediate conveyor to the discharge conveyor and can easily reel and tilt over. The consequence thereof is a damaged second side inspection device, as well as serious operational failures. Moreover, the function of the bottom inspection device may be impaired by the self-rotation of the containers in the area of the bottom inspection device.
It is therefore the object of the present invention to improve the inspection machine of the above-mentioned type with respect to efficiency and operational reliability of the container transport and with respect to inspection accuracy as far as side wall inspection is concerned.